Addendum 1 Montessori RFP Questions.pdf

Breckenridge Montessori Restoration and Expansion Town of Breckenridge

Addendum #1

RFP Update and Questions

Failure to acknowledge receipt of this addendum will result in your proposal not being read. Receipt of all addenda shall be acknowledged in Section III of the RFP.

Updated RFP due date of March 21, 2025, 12 PM.

Q1: In the RFP it states that the Town may ask for certain financial information, and then in the RFP form it states to attach financial information. Can the Town clarify if that should be included with the RFP submission or at a later date upon request? Furthermore, would alternative financial submission be accepted in lieu of an audited or sealed letter?

A1: Any requested financial information will be requested from the contractor that is awarded the project and does not need to be included in the proposal.

Q2: Can we include the Geotech report?

A2: Yes, the Geotech report is included in this addendum.

240 Annie Road | PO Drawer 1887

Silverthorne, Colorado 80498

Fax: (970) 468-5891

Phone: (970) 468-1989

Email: hpksummit@kumarusa.com

Office Locations: Denver (HQ), Colorado Springs, Fort Collins, Glenwood Springs Parker and Summit County, Colorado

GEOTECHNICAL ENGINEERING STUDY

PROPOSED BUILDING ADDITIONS

BRECKENRIDGE MONTESSORI SCHOOL

318 NORTH MAIN STREET

BRECKENRIDGE, COLORADO

Prepared by: Reviewed by:

James A. Parker, P.E., P.G. Steven L. Pawlak, P.E.

PREPARED FOR:

TOWN OF BRECKENRIDGE

ATTN: AARON NEFF, P.E.

P.O. BOX 168

BRECKENRIDGE, COLORADO 80424

aneff@townofbreckenridge.com

Project No. 24-6-229 December 3, 2024 Revised: December 5, 2024 mailto:aneff@townofbreckenridge.com

Kumar and Associates

TABLE OF CONTENTS

PURPOSE AND SCOPE OF STUDY

PROPOSED CONSTRUCTION

SITE CONDITIONS

SUBSURFACE CONDITIONS

LABORATORY TESTING

GEOTECHNICAL ENGINEERING CONSIDERATIONS

SITE GRADING

FOUNDATIONS

FOUNDATION AND RETAINING WALLS

FLOOR SLABS

EXTERIOR FLATWORK

UNDERDRAIN SYSTEM AND DAMP-PROOFING

SURFACE DRAINAGE

CONTINUING SERVICES

LIMITATIONS

Fig. 1 LOCATION OF EXPLORATORY BORINGS

Fig. 2 LOGS OF EXPLORATORY BORINGS

Fig. 3 LEGEND AND NOTES

Fig. 4 GRADATION TEST RESULTS

Fig. 5 TYPICAL DRAIN DETAIL

Table 1 – SUMMARY OF LABORATORY TEST RESULTS

PURPOSE AND SCOPE OF STUDY

This report presents the results of a geotechnical engineering study for proposed additions to the existing Breckenridge Montessori School building located at 318 North Main Street, in

Breckenridge, Colorado, as shown on Fig. 1. The purpose of the study was to develop recommendations for the foundation and floor slab design. The study was conducted in accordance with our Proposal No. P6-24-272 for geotechnical engineering services with Town of Breckenridge, dated October 15, 2024.

A field exploration program consisting of exploratory borings and a site reconnaissance was conducted to obtain information on the surface and subsurface conditions. Samples of the subsoils obtained during the field exploration were tested in the laboratory to determine their classification and other engineering characteristics. The results of the field exploration and laboratory testing were analyzed to develop recommendations for foundation types, depths, and allowable pressures for the proposed structure foundation and floor slab design.

This report summarizes the data obtained during this study and presents our conclusions, design recommendations and other geotechnical engineering considerations based on the proposed construction and the subsoil conditions encountered.

PROPOSED CONSTRUCTION

Conversations with the Project Team indicate the proposed building expansion will include additions to the front and rear of the existing building. We assume the additions will be one or two-level structures, possibly with basement levels. Excavation cut depths for the additions are assumed to be up to about 10 feet for basement level construction. Structural loads are anticipated to be light and typical of the proposed construction.

If construction plans are different than those described above, we should be notified to re-evaluate the recommendations presented in this report.

SITE CONDITIONS

The project site is a 0.27-acre lot located on the east side of Main Street in Breckenridge, Colorado, as shown on Fig. 1. The site is relatively flat and occupied with a single-level, wood-frame school building in the central portion of the lot, with a playground on the west side of the building, an asphalt-paved access drive to the south, and an asphalt-paved parking area to the east of the building.

FIELD EXPLORATION

The field exploration for the project was conducted on November 11, 2024. Two exploratory borings were drilled in proposed development areas to evaluate the subsurface conditions, as shown on Fig. 1. The borings were advanced with 4-inch diameter continuous flight solid stem augers powered by a truck-mounted CME-45 drill rig. The borings were logged by a representative of Kumar and Associates, Inc.

Samples of the subsoils were taken with a 2-inch I.D. modified California metal liner sampler.

The sampler was driven into the subsoils at various depths with blows from a 140-pound hammer falling 30 inches. This test is similar to the standard penetration test described by

ASTM Method D-1586. The penetration resistance values are an indication of the relative density of the granular subsoils. A disturbed bulk sample of the subsoils was also obtained from

Boring 2. Depths at which the samples were taken, and the penetration resistance values, are shown on the Logs of Exploratory Borings, Figure 2. The samples were returned to our laboratory for review by the project engineer and for laboratory testing.

SUBSURFACE CONDITIONS

Soil Types Encountered: Graphic logs of the subsurface conditions encountered at the site are shown on Figure 2. The borings were drilled through approximately 4-inches of asphalt pavement overlying about 8 inches of aggregate base course. Subsoils encountered underlying the base course consisted of medium dense to dense, silty sand (SM) with gravel and cobbles, extending to a depth of about 4 feet, at which depth the SM transitioned to silty gravel (GM) with sand, cobbles, and scattered boulders. The GM soil extended to a depth of 11 feet in Boring 1, and 12 feet in Boring 2, at which depths practical refusal to auger drilling was encountered on boulders. Some of the high blow counts presented on the boring logs may be due to large size gravels and cobbles in the subgrade.

Groundwater: Groundwater was not encountered in the borings at the time of drilling. The depth to groundwater can vary based on seasonal and climatic factors, and perched water can occur seasonally over frozen ground.

LABORATORY TESTING

Laboratory testing performed on samples obtained from the exploratory borings consisted of natural moisture content, percent passing the No. 200 sieve and gradation analysis. The results of gradation analyses performed on the minus 1½-inch fraction of the natural granular soils are shown on Figure 4. The laboratory test results are shown on the Logs of Exploratory Borings, Figure 2, and summarized in Table 1.

GEOTECHNICAL ENGINEERING CONSIDERATIONS

Subsurface data indicate that medium dense to dense, natural sand and gravel with cobbles and boulders, will likely be the predominant soil types encountered beneath shallow foundation, floor slab and concrete flatwork areas. The anticipated natural granular soils at the foundation level are considered good for shallow foundation support. Asphalt pavement, if removed from development areas, should be exported off-site. Aggregate base course, underlying the existing asphalt pavement, should be suitable for use as structural fill, if free from deleterious materials.

Practical refusal to auger drilling on boulders was encountered in the borings, and based on the conditions encountered and our experience at nearby project sites, relatively large boulders prevented auger from advancing and should be anticipated in foundation and utility excavations.

Suitable heavy duty excavation equipment should be mobilized by the excavation contractor for the anticipated conditions.

The natural gravel soils are relatively clean (low percentage of material passing the No. 200 sieve) and basement level excavations will likely require shoring to prevent collapse of excavation sidewalls. Basement level excavations adjacent to at-grade portions of the existing structure should be performed in a manner that does not de-stabilize the existing building foundations, and support of the existing building foundations could be needed.

Kumar and Associates should observe the building addition footing excavations prior to placement of footing concrete or structural fill to assess bearing conditions. Structural fill placement should be observed, and the fill tested for compaction by Kumar and Associates to document that the recommendations in this report are implemented.

SITE GRADING

The following recommendations should be followed for grading, site preparation, and fill compaction.

1. Where fill is to be placed, asphalt pavement, existing aggregate base course fill, loose, or otherwise unsuitable material should be removed prior to placement of new fill. The exposed soils should then be scarified to a depth of 8 inches, moisture conditioned and compacted preferably by vibratory compaction equipment to the minimum requirements of the overlying fill. Soils should be compacted with appropriate equipment for the lift thickness placed. Lift thickness should be no more than 8 loose inches compacted at the recommended moisture content and to the minimum required density.

2. Permanent unretained cut and fill slopes should be graded at 2 horizontal to 1 vertical

(2:1) or flatter and protected against erosion by revegetation or other means. The risk of slope instability will be increased if seepage is encountered in cuts and flatter slopes may be necessary. If seepage is encountered in permanent cuts, an investigation should be conducted to determine if the seepage will adversely affect the cut stability.

This office should review site grading plans for the project prior to construction.

3. Slopes of 4:1 or steeper should be benched to provide a sufficiently wide level bench surface for compaction. All backfill should be processed so that it does not contain rock fragments and/or cobbles larger than 6-inches in diameter and placed at the recommended moisture content.

4. The fill should be uniformly graded to prevent nesting of large size gravel and cobbles.

5. The following compaction requirements should be used:

TYPE OF FILL

PLACEMENT

MOISTURE

CONTENT

SOIL TYPE - Compaction Percent

(ASTM D698 – Standard Proctor)

Below Foundations 2% Optimum Structural Fill – 98%

Foundation Wall

Backfill 2% Optimum Processed On-site or Structural Fill – 95%

Below Floor Slabs 2% Optimum Structural Fill – 95%

Landscape Areas 2% Optimum Processed On-site – 90%

Below Concrete

Flatwork/Pavements 2% Optimum Structural Fill – 95%

Utility Trenches As they apply to the finished area

Suitability of On-Site Soil The on-site sand and gravel soils are suitable as backfill after processing to remove all plus 6-inch material and moisture treatment. The existing aggregate base course fill, screened for oversize rock and deleterious material, should be suitable for use as structural fill, but should be further evaluated for suitability by Kumar & Associates at the time of excavation. Asphalt pavement, removed from development areas, is not suitable for use as structural fill and should be exported off-site.

Structural Fill Structural fill used for support of the proposed construction should consist of the on-site processed soils, approved processed existing aggregate base course fill, or a relatively well-graded imported granular material with 5 to 25 percent material passing the No. 200 sieve, 60 percent or more passing the No. 4 sieve and no rocks larger than 6 inches. Structural fill should be properly placed and compacted to reduce the risk of settlement and distress. The

Geotechnical engineer should evaluate the suitability of any proposed import fill for its intended use.

Excavation Considerations In our opinion, it is anticipated that the on-site soils encountered in the exploratory borings drilled for this study can be excavated with conventional heavy-duty construction equipment.

Large-sized boulders should be anticipated in excavations, requiring suitable sized excavation equipment to move and possible off-site disposal.

Temporary Excavation Slopes: We assume that the temporary excavations will be constructed by excavating the slopes to a stable configuration or stabilized using properly designed shoring.

All excavations should be constructed in accordance with OSHA requirements, as well as state, local and other applicable requirements.

In our opinion, the natural granular soil and existing fill should be classified as OSHA Type C soils. Excavations where perched water exists and seeps into the excavation are possible and could require much flatter side slopes than those allowed by OSHA. All excavations greater than 20 feet should be designed by a registered professional engineer.

Where insufficient lateral space is available due to the proximity to property boundaries and existing structures and facilities, temporary shoring may be required. It is our experience that temporary shoring systems are typically designed and built by specialty contractors and that the designers will typically develop their own design criteria based on soil data presented in the owner’s geotechnical study report.

FOUNDATIONS

Considering the subsoil conditions encountered in the exploratory borings and the nature of the proposed construction, we recommend the building additions be founded with spread footings bearing on the undisturbed natural granular soils or properly compacted new structural fill extending to natural soils.

The design and construction criteria presented below should be observed for a spread footing foundation system.

1) Footings placed on the undisturbed natural granular soils or compacted new structural fill should be designed for an allowable soil bearing pressure of 3,000 pounds per square foot (psf). Based on experience, we expect settlement of footings designed and constructed as discussed in this section will be about 1 inch or less, with movement likely to be differential with respect to the existing structure.

2) The footings should have a minimum width of 18 inches for continuous walls and 2 feet for isolated pads.

3) Exterior footings and footings beneath unheated areas should be provided with adequate soil cover above their bearing elevation for frost protection. Placement of foundations at least 40 inches below exterior grade is recommended for foundations bearing on the sand and gravel soils. Concrete should not be placed on frost, frozen soil, snow, or ice. Interior footings and/or thickened slab sections should bear a minimum of 12 inches below base of floor slab, or in accordance with local building code requirements.

4) Continuous foundation walls should be reinforced top and bottom to span local anomalies such as by assuming an unsupported length of at least 12 feet. Foundation walls acting as retaining structures should also be designed to resist lateral earth pressures as discussed in the "Foundation and Retaining Walls" section of this report.

5) Existing fill, and any loose or disturbed soils should be removed, and the footing bearing level extended down to the relatively undisturbed granular soils or replaced with properly compacted structural fill.

6) The exposed soil in footing areas should then be adjusted to near optimum moisture content and compacted. If water seepage is encountered, the footing areas should be dewatered before concrete placement and we shall be contacted for further evaluation.

7) Voids in the footing area subgrade created by boulder removal should be backfilled with properly compacted structural fill, lean mix “flow-fill” concrete or structural concrete.

8) Structural fill used for support of the foundation should meet the requirements listed in the SITE GRADING section of this report.

9) A representative of the geotechnical engineer should observe all footing excavations prior to forming footings and concrete placement to evaluate bearing conditions.

FOUNDATION AND RETAINING WALLS

Foundation walls and retaining structures, such as basement level walls, which are laterally supported and can be expected to undergo only a slight amount of deflection should be designed for a lateral earth pressure computed on the basis of an equivalent fluid unit weight of at least 45 pounds per cubic foot (pcf) for backfill consisting of the on-site processed soils or suitable granular import. Cantilevered retaining structures which are separate from the building foundation and can be expected to deflect sufficiently to mobilize the full active earth pressure condition should be designed for a lateral earth pressure computed on the basis of an equivalent fluid unit weight of at least 35 pcf for backfill consisting of the processed on-site soil or suitable granular import. The backfill should not contain rock larger than about 6 inches in diameter.

The lateral resistance of foundation or retaining wall footings will be a combination of the sliding resistance of the footing on the foundation materials and passive earth pressure against the side of the footing. Resistance to sliding at the bottoms of the footings can be calculated based on a coefficient of friction of 0.45. Passive pressure of compacted backfill against the sides of the footings can be calculated using an equivalent fluid unit weight of 420 pcf.

The coefficient of friction and passive pressure values recommended above assume ultimate soil strength. Suitable factors of safety should be included in the design to limit the strain which will occur at the ultimate strength, particularly in the case of passive resistance. Fill placed against the sides of the footings to resist lateral loads should be a suitable granular material compacted to at least 95% of the maximum standard Proctor dry density at a moisture content near optimum.

All foundation and retaining structures should be designed for appropriate hydrostatic and surcharge pressures such as adjacent footings, traffic, construction materials and equipment.

The pressures recommended above assume drained conditions behind the walls and a horizontal backfill surface. The buildup of water behind a wall or an upward sloping backfill surface will increase the lateral pressure imposed on a foundation wall or retaining structure.

An underdrain should be provided to limit hydrostatic pressure buildup behind walls.

Backfill in pavement, and walkway areas should be placed in uniform lifts and compacted to at least 95% of the maximum standard Proctor (ASTM D-698) dry density. Backfill placed in landscape areas should be compacted to at least 90% of the maximum standard Proctor dry density at a moisture content near optimum. Care should be taken not to overcompact the backfill or use large equipment near the wall, since this could cause excessive lateral pressure on the wall. Some settlement of deep foundation wall backfill should be expected, even if the material is placed correctly, and could result in distress to facilities constructed on the backfill.

FLOOR SLABS

The on-site natural granular soils or properly compacted new structural fill are suitable to support lightly loaded slab-on-grade construction. Asphalt pavement and existing aggregate base course fill should be removed in floor slab areas to expose the underlying natural granular soil and replaced with new structural fill.

To reduce the effects of some differential movement, floor slabs should be separated from all bearing walls and columns with expansion joints which allow unrestrained vertical movement.

Floor slab control joints should be used to reduce damage due to shrinkage cracking. The requirements for joint spacing and slab reinforcement should be established by the designer based on experience and the intended slab use. All backfill under floor slabs should be placed in accordance with the SITE GRADING section of this report.

We recommend vapor retarders conform to at least the minimum requirements of ASTM E1745

Class C material. Certain floor types are more sensitive to water vapor transmission than others. For floor slabs bearing on angular gravel or where flooring system sensitive to water vapor transmission are utilized, we recommend a vapor barrier be utilized conforming to the minimum requirements of ASTM E1745 Class A material. The vapor retarder should be installed in accordance with the manufacturers’ recommendations and ASTM 1643.

EXTERIOR FLATWORK

Structural fill placed beneath concrete flatwork, such as pedestrian only sidewalks and patios, can consist of processed on-site granular soils or an imported, well-graded granular material, meeting the requirements for structural fill in the SITE GRADING section of this report.

Structural fill should be spread in thin horizontal lifts, adjusted to at or above optimum moisture content, and compacted to at least 95% of the maximum standard Proctor dry density. Existing fill, loose, or disturbed soil should be removed prior to fill placement.

Flatwork should follow Summit County requirements. Generally, a minimum exterior concrete flatwork section of 4 inches of concrete over 6 inches of ABC is suitable for concrete flatwork on the project site.

UNDERDRAIN SYSTEM AND DAMP-PROOFING

Groundwater was not encountered during our exploration, but it has been our experience in mountainous areas that groundwater levels can rise, and that local perched groundwater can develop during times of heavy precipitation or seasonal runoff. Frozen ground during spring runoff can create a perched condition. We recommend below-grade construction such as retaining walls, crawlspace, and basement areas, be protected from wetting and hydrostatic pressure buildup by an underdrain and wall drain system. Slabs on grade, constructed at grade, should not require an underdrain or dampproofing.

The underdrain should consist of drainpipe placed in the bottom of the wall backfill surrounded above the invert level with free-draining gravel. The drain should be placed at each level of excavation and at least 12-inches below lowest adjacent finish grade and sloped at a minimum

1% to a suitable gravity outlet, sump and pump system or drywell. Free-draining gravel used in the underdrain system should contain less than 2% passing the No. 200 sieve, less than 50% passing the No. 4 sieve and have a maximum size of 1-inch. The drain gravel backfill should be at least 1½ feet deep and protected by filter fabric. A typical drain detail is shown on Figure 5.

For exterior below grade foundation walls, we recommend, as a minimum, damp-proofing consist of bituminous material, 3 lbs per square yard, extending from the top of the footing to above ground level. A wall drain system consisting of a geocomposite, MiraDrain 6000, or equivalent, should be placed adjacent to below grade construction walls, with 100 percent coverage on the foundation wall facing the uphill slope and a minimum of 50 percent coverage for the adjacent foundation walls. The wall drain system should connect into the underdrain and extend to within 1 to 2 feet of the ground surface.

SURFACE DRAINAGE

The following drainage precautions should be observed during construction and maintained at all times after the building has been completed:

1) Inundation of the foundation excavations and underslab areas should be avoided during construction.

2) Backfill in pavement and slab areas should be compacted to at least 95% of the maximum standard Proctor dry density at a moisture content within 2% of optimum.

Exterior backfill placed in landscape areas should be compacted to at least 90% of the maximum standard Proctor dry density at a moisture content near optimum.

3) The ground surface surrounding the exterior of the building should be sloped to drain away from the foundation in all directions. We recommend a minimum slope of 6 inches in the first 10 feet in unpaved areas and a minimum slope of 2½ inches in the first 10 feet in paved areas.

4) Roof downspouts and drains should discharge well beyond the limits of all backfill.

CONTINUING SERVICES

Two additional elements of geotechnical engineering service are important to the successful completion of this project.

1) Consultation with design professionals during the design phases. This is important to ensure that the intentions of our recommendations are properly incorporated in the design, and that any changes in the design concept properly consider geotechnical aspects.

2) Observation and monitoring during construction. A representative of the Geotechnical engineer from our firm should observe the foundation excavation, earthwork, and foundation phases of the work to determine that subsurface conditions are compatible with those used in the analysis and design and our recommendations have been properly implemented. Placement of backfill should be observed and tested to judge whether the proper placement conditions have been achieved. We recommend a representative of the geotechnical engineer observe the drain and dampproofing phases of the work, if constructed, to judge whether our recommendations have been properly implemented.

LIMITATIONS

This study has been conducted in accordance with generally accepted geotechnical engineering principles and practices in this area at this time. We make no warranty either express or implied. The conclusions and recommendations submitted in this report are based upon the data obtained from the exploratory borings at the locations indicated on Figure 1, the proposed type of construction and our experience in the area. Our services do not include determining the presence, prevention or possibility of mold or other biological contaminants (MOBC) developing in the future. If the client is concerned about MOBC, then a professional in this special field of practice should be consulted. Our findings include interpolation and extrapolation of the subsurface conditions identified at the exploratory borings and variations in the subsurface conditions may not become evident until excavation is performed. If conditions encountered during construction appear different from those described in this report, we should be notified so that re-evaluation of the recommendations may be made.

This report has been prepared for the exclusive use by our client for design purposes. We are not responsible for technical interpretations by others of our information. As the project evolves, we should provide continued consultation and field services during construction to review and monitor the implementation of our recommendations, and to verify that the recommendations have been appropriately interpreted.

Boring-1

Existing Building

0 50' 100'

*Boring Locations are Approximate

Approximate Scale

0 50' 100'

*Boring Locations are Approximate

Approximate Scale

Boring-2

Kumar & Associates

FOUNDATION WALL

BACKFILL SURFACE

10 PERCENT MINIMUM

SLOPE FOR LANDSCAPE

AREAS OR 3 PERCENT FOR

FLATWORK / ASPHALT FOR

10 FEET

FILTER FABRIC

DRAIN GRAVEL

DRAIN PIPE

TOP OF SLAB / LOWER LEVEL FLOOR

1' MINIMUM

VAPOR RETARDER

RELATIVELY IMPERVIOUS

BACKFILL IN THE UPPER 2

FEET OR FLATWORK /

ASPHALT

1. DRAIN PIPE - consists of 4-inch perforated PVC, surrounded by a minimum of 4 inches of drain gravel on the top and sides, sloped at 1 percent to a gravity discharge or drywell.

Bottom of pipe at the high point should be a minimum of 12-inches below the top of the floor.

2. DRAIN GRAVEL - consists of minus 1-inch aggregate with less than 50 percent passing the No. 4 sieve and less than 2 percent passing the No. 200 sieve. Drain gravel should fill the entire trench a be a minimum of 18 inches deep. A minimum of 4 inches of drain gravel is recommended under basement level concrete floors to facilitate drainage. The drain gravel under the slab should be connected to the perimeter drain system or connected directly to the drywell by perforated, rigid pipe under the slab or perforation in the drywell by means of piping under the footing on the downhill side of the building or other approved method.

3. VAPOR RETARDER - consists of a minimum 10-mil vapor retarder meeting the minimum requirements of ASTM E1745 Class C material, adequately overlaped and sealed. Vapor retarder should be installed in accordance with the manufacturers specifications.

4. FILTER FABRIC - protect drain gravel and drain pipe with Mirafi 180N, or equivalent.

DAMPPROOFING

DRAIN GRAVEL

WALL DRAIN

5. WALL DRAIN - consists of MiraDRAIN 6000 or equivalent.

NOT TO SCALE

JOB NO: 24-6-229

PROPOSED ADDITION - BRECKENRIDGE MONTESSORI TABLE 1

NATURAL NATURAL HVEEM WATER SOIL OR

MOISTURE DRY UNIT SILT & LIQUID PLASTIC SUR- STABILOMETER SOLUBLE BEDROCK

BORING DEPTH CONTENT WEIGHT GRAVEL SAND CLAY LIMIT INDEX SWELL CHARGE (R-VALUE) SULFATES DESCRIPTION

(#) (feet) (%) (pcf) (%) (%) (%) (%) (%) (%) (psf) (%)

1 2 4.5 36 SILTY SAND WITH GRAVEL

4 5.1 28 SILTY GRAVEL WITH SAND

2 2 3.1 18 SILTY SAND WITH GRAVEL

5'-10' 1.8 42 42 16 SILTY SAND AND GRAVEL

JOB NAME:

SUMMARY OF LABORATORY TEST RESULTS

SAMPLE

LOCATION

GRADATION ATTERBERG LIMITS SWELL-COMPRESSION